New owner about to sell......questions for the experts.

[Short Timer_imp]

Well, down the rabbit hole...... On the subject of oil, my past bikes, as far back as I remember, had temperature ranges in the owners manual that gave at least a couple of options on oil weights. Usually 10-30 for milder climates or riding conditions, and, say, a 10-40 for higher temperature zones or more severe riding conditions. I don't see anything like that in my owners manual? Did I miss something? I hate to arbitrarily switch weights "just because" if the manual doesn't refer to it. (Just call me overly cautious!)